Method for inductively heating a surgical implement

ABSTRACT

A power source delivers oscillating electrical energy to an electrical conductor, such as a wire or catheter, which is coated circumferentially with a ferromagnetic material in a selected region. With high frequency electrical energy, the ferromagnetic material has a quick response in heating and cooling adjustable by the controllable power delivery. The ferromagnetic material can be used for separating tissue, coagulation, tissue destruction or achieving other desired tissue effects in numerous surgical procedures.

RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/170,203, filed Apr. 17, 2009, U.S. ProvisionalPatent Application Ser. No. 61/170,220, filed Apr. 17, 2009, and U.S.Provisional Patent Application Ser. No. 61/170,207, filed Apr. 17, 2009which are incorporated hereby by references in their entirety.

This application is part of a group of similar applications includingU.S. patent application Ser. No. 12/647,340, filed Dec. 24, 2009,Attorney Docket Number 4340.NEXS.NP; U.S. patent application Ser. No.12/647,344, filed Dec. 24, 2009, Attorney Docket Number 4340.NEXS.NP2;U.S. patent application Ser. No. 12/647,350, filed Dec. 24, 2009,Attorney Docket Number 4340.NEXS.NP3; U.S. patent application Ser. No.12/647,355, filed Dec. 24, 2009, Attorney Docket Number 4340.NEXS.NP4;U.S. patent application Ser. No. 12/647,358, filed Dec. 24, 2009,Attorney Docket Number 4340.NEXS.NP5; U.S. patent application Ser. No.12/647,363, filed Dec. 24, 2009, Attorney Docket No. 4340.NEXS.NP6; U.S.patent application Ser. No. 12/647,371, filed Dec. 24, 2009, AttorneyDocket Number 4389.NEXS.NP; U.S. patent application Ser. No. 12/647,329,filed Dec. 24, 2009, Attorney Docket Number 4390.NEXS.NP1; U.S. patentapplication Ser. No. 12/647,374, filed Dec. 24, 2009, Attorney DocketNumber 4390.NEXS.NP2; U.S. patent application Ser. No. 12/647,376, filedDec. 24, 2009, Attorney Docket Number 4390.NEXS.NP3; and U.S. patentapplication Ser. No. 12/647,380, filed Dec. 24, 2009, Attorney DocketNumber 4390.NEXS.NP4, each of which is incorporated hereby by referencesin its entirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to surgical tools. More specifically, thepresent invention relates to thermally adjustable tools used in open andminimally invasive surgical procedures and interventional surgical andtherapeutic procedures.

2. State of the Art

Surgery generally involves cutting, repairing and/or removing tissue orother materials. These applications are generally performed by cuttingtissue, fusing tissue, or tissue destruction.

Current electrosurgery modalities used for cutting, coagulating,desiccating, ablating, or fulgurating tissue, have undesirable sideeffects and drawbacks.

Monopolar and bipolar electrosurgery modalities generally havedisadvantages relating to “beyond the tip” effects. These effects arecaused by passing alternating current through tissues in contact withconducting instruments or probes.

Monopolar surgical instruments require electric current to pass throughthe patient. A return electrode is placed on the patient, often on thepatient's thigh. Electricity is conducted from a “knife” electrodethrough the tissue and returns through the return electrode. Other formsof monopolar instruments exist, such as those which use the capacitiveeffect of the body to act as the return electrode or ground.

A low voltage high frequency waveform will incise, but has littlehemostatic effect. A high voltage waveform will cause adjacent tissuehemostasis and coagulation. Therefore, when hemostasis is desirable,high voltage is used. The high voltage spark frequently has deepertissue effects than the cut because the electricity must pass throughthe patient. The damage to the tissue extends away from the actual pointof coagulation. Furthermore, there are complaints of return electrodeburns. Yet, any reduction of voltage reduces the effectiveness ofhemostasis. Further, the temperature of the spark or arc cannot beprecisely controlled, which can lead to undesirable charring of targettissue.

Bipolar surgical instruments can produce tissue damage and problems thatare similar to monopolar devices, such as sparking, charring, deepertissue effects and electric current damage away from the application ofenergy with varying effects due to the differing electrical conductivityof tissue types, such as nerve, muscle, fat and bone, and into adjacenttissues of the patient. However, the current is more, but notcompletely, contained between the bipolar electrodes. These electrodesare also generally more expensive because there are at least twoprecision electrodes that must be fabricated instead of the onemonopolar electrode.

Electrocautery resistive heating elements reduce the drawbacksassociated with charring and deeper tissue damage caused by otherelectrosurgery methods. However, such devices often present othertradeoffs, such as the latency in controlling heating and cooling time,and effective power delivery. Many resistive heating elements have slowheating and cooling times, which makes it difficult for the surgeon towork through or around tissue without causing incidental damage.

Tissue destruction instruments generally heat tissue to a predeterminedtemperature for a period of time to kill, or ablate, the tissue. In somecontrolled heating of tissues, a laser is directed to an absorptive capto reach and maintain a predetermined temperature for a predeterminedamount of time. While this provides the benefits of thermal heating, itis expensive due to the complexity and expense of laser hardware.

In another tissue destruction procedure, a microwave antenna array isinserted into the tissue. These arrays are powered by instruments thatcause microwave energy to enter and heat the tissue. While such devicesare often effective at killing, or ablating, the desired tissue, theyoften cause deeper tissue effects than the desired area. Additionallythe procedures can require expensive equipment.

Tissue destruction with resistively heated tools can produce unintendedcollateral tissue damage, in addition to having slow heating and coolingattributes.

Use of ferrite beads and alloy mixes in ceramics have been examined asalternatives. When excited by the magnetic field associated with highfrequency current passing through a conductor, ferrite beads and alloymixes in ceramics can reach high temperatures very quickly. However, onemajor problem with the use of these materials is that a largetemperature differential can cause the material to fracture, especiallywhen it comes into and out of contact with liquids. In other words, if ahot ferrite surgical instrument is quenched by a cooler pool of liquid,such as blood or other body fluids, the material's correspondingtemperature drops rapidly and may cause the material to fracture. Thesefractures not only cause the tool to lose its effectiveness as a heatsource, because the magnetic field is disrupted, but may requireextraction of the material from the patient. Obviously, the need toextract small pieces of ferrite product from a patient is highlyundesirable. Thus, there is a need for an improved thermal surgicaltool.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improvedthermally adjustable surgical or therapeutic tool and a method of usingthe same.

According to one aspect of the invention, a thermal surgical tool systemis provided with a ferromagnetic coating over a conductor and anoscillating electrical energy source for generating heat at the locationof the coating. The oscillating electrical energy may cause inductiveheating of the ferromagnetic coating to thereby enable the cutting,ablating, etc., of tissue.

In accordance with another aspect of the invention, the thermal surgicaltool system is provided with a power control mechanism which enables thesurgeon to quickly adjust the power to the surgical or therapeutic toolto achieve desired tissue welding, cutting, ablation, vaporization,etc., depending on the amount of power supplied to the tool. This mayprovide the advantage of allowing the surgeon to only deliver a thermaleffect at desired locations, which may also prevent the accidentaldelivery of undesired thermal effects while waiting for the tool tocool.

According to another aspect of the invention, a thermal surgical toolsystem may be configured so that the power delivery to a ferromagneticelement may be altered by the surgeon in near real-time to achievedifferent tissue effects, including hemostasis, tissue welding andtissue destruction.

According to another aspect of the invention, controlled thermal tissuedestruction may be performed.

According to another aspect of the invention, the coated conductor maybe powered by a generator and incorporated in a catheter or endoscope,which could also provide for sensing, viewing, aspiration, irrigation,delivery of a thermally-cured material, or removal of a thermally-meltedor ablated material, through a channel.

According to another aspect of the invention a catheter may be used todeliver a ferromagnetic coated conductor into an area for a desiredtherapeutic effect.

According to another aspect of the invention, the heating of theferromagnetic coating may be directed by changing characteristics of thepower delivered to the conductor.

According to another aspect of the invention, a plurality offerromagnetic conductors may be disposed on a primary geometry, eachconductor being individually controlled such that the ferromagneticconductors may provide different tissue effects at the same time.

These and other aspects of the present invention are realized in athermally adjustable surgical tool as shown and described in thefollowing figures and related description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention are shown and described inreference to the numbered drawings wherein:

FIG. 1 shows a perspective view of a thermal surgical tool system inaccordance with the principles of the present invention;

FIG. 2 shows a perspective view of an alternate embodiment of a thermalsurgical tool system in accordance with the present invention;

FIG. 3 shows a diagram of a thermal surgical tool system in accordancewith the principles of the present invention;

FIG. 4A shows a thermal surgical tool system with heat preventionterminals, heat sink, and wireless communication devices;

FIG. 4B shows a thermal surgical tool system with impedance matchingnetwork;

FIG. 5A shows a close-up, side cross-sectional view of a single layerferromagnetic coated conductor tip in accordance with one aspect of thepresent invention;

FIG. 5B shows an electrical equivalent representation of FIG. 5A'sferromagnetic coated conductor;

FIG. 6 shows a close-up, side cross-sectional view of a single layerferromagnetic coated conductor tip with a thermal insulator inaccordance with one aspect of the present invention;

FIG. 7A shows a close-up view of ferromagnetic coated conductor surgicaltool tip with a loop geometry in accordance with one aspect of thepresent invention;

FIG. 7B shows a close-up view of a ferromagnetic coated conductorsurgical tool tip with a generally square geometry in accordance withone aspect of the present invention;

FIG. 7C shows a close-up view of a ferromagnetic coated conductorsurgical tool tip with a pointed geometry;

FIG. 7D shows a close-up view of a ferromagnetic coated conductorsurgical tool tip with an asymmetrical loop geometry;

FIG. 7E shows a close-up view of a ferromagnetic coated conductorsurgical tool tip with a hook geometry in which the concave portion maybe used for therapeutic effect, including cutting;

FIG. 7F shows a close up view of a ferromagnetic coated conductorsurgical tool tip with a hook geometry in which the convex portion maybe used for therapeutic effect, including cutting;

FIG. 7G shows a close up view of a ferromagnetic coated conductorsurgical tool tip with an angled geometry;

FIG. 8 shows a cut-away view of a retracted snare;

FIG. 9A shows a side view of an extended snare;

FIG. 9B shows an alternate embodiment of an extended snare;

FIG. 10A shows a close-up view of a ferromagnetic coated conductorsurgical tool with a loop geometry and linear array of coatings;

FIG. 10B shows a close up view of a ferromagnetic coated conductorsurgical tool with an alternate hook geometry and linear array;

FIG. 11 shows a cut-away view of a retracted snare with an array ofcoatings;

FIG. 12 shows a side view of an extended snare with a linear array ofcoatings;

FIG. 13 shows an axial cross-sectional view of a single layerferromagnetic coated conductor surgical tool in the ferromagnetic-coatedregion;

FIG. 14A shows a perspective view of a multi-layer ferromagnetic coatedconductor surgical tool tip;

FIG. 14B shows a side cross-sectional view of a multi-layerferromagnetic coated conductor surgical tool tip shown in 14A;

FIG. 15 shows an axial cross-section of the multi-layer ferromagneticcoated conductor surgical tool tip shown in FIG. 14A;

FIG. 16 shows a cross-sectional view of a flattened side cylindricalgeometry ferromagnetic coated conductor showing electromagnetic lines offlux;

FIG. 17 shows a closed conductor tip in accordance with another aspectof the present invention;

FIG. 18A shows a single edge ferromagnetic coated conductor surgicaltool tip in accordance with one aspect of the invention;

FIG. 18B shows a double edge ferromagnetic coated conductor surgicaltool tip;

FIG. 18C shows a three wire ferromagnetic coated conductor surgical tooltip;

FIG. 18D shows a receptacle for the tips shown in FIGS. 18A through 18C;

FIG. 19A shows a normally cold cutting scalpel with alternate inductiveferromagnetic thermal function;

FIG. 19B shows an alternate embodiment of a normally cold cuttingscalpel with alternate inductive ferromagnetic thermal function;

FIG. 20A shows a thermal surgical tool with a spatula shaped geometry;

FIG. 20B shows a thermal surgical tool with a spatula shaped geometry ina forceps configuration;

FIG. 20C shows a top view of the thermal surgical tool of FIG. 20A withthe ferromagnetic coated conductor upon the primary geometry;

FIG. 20D shows a top view of the thermal surgical tool of FIG. 20A withthe ferromagnetic coated conductor embedded within the primary geometry;

FIG. 21A shows a thermal surgical tool with a ball shaped geometry andhorizontal winding;

FIG. 21B shows an alternate embodiment of a thermal surgical tool with aball shaped geometry and horseshoe configuration;

FIG. 21C shows an alternate embodiment of a thermal surgical tool with aball shaped geometry and vertical orientation;

FIG. 22A shows a thermal surgical tool with a pointed geometry;

FIG. 22B shows a thermal surgical tool with a pointed geometry in aforceps configuration;

FIG. 22C shows a thermal surgical tool having two different activatablethermal zones;

FIG. 23A shows a perspective view of a catheter having a coil offerromagnetic coated conductor disposed around the tip of the catheter;

FIG. 23B shows a perspective view of an ferromagnetic coated conductorsurgical tool catheter tip;

FIG. 24 shows a side view of an alternate embodiment of an ferromagneticcoated conductor surgical tool catheter tip;

FIG. 25 shows an alternate embodiment of a ferromagnetic coatedconductor surgical tool ferromagnetic tip disposed within an endoscope;

FIG. 26 shows a tissue ablation tool; and

FIG. 27 shows a thermal spectrum as related to tissue effects.

It will be appreciated that the drawings are illustrative and notlimiting of the scope of the invention which is defined by the appendedclaims. The embodiments shown accomplish various aspects and objects ofthe invention. It is appreciated that it is not possible to clearly showeach element and aspect of the invention in a single figure, and assuch, multiple figures are presented to separately illustrate thevarious details of the invention in greater clarity. Similarly, notevery embodiment need accomplish all advantages of the presentinvention.

DETAILED DESCRIPTION

The invention and accompanying drawings will now be discussed inreference to the numerals provided therein so as to enable one skilledin the art to practice the present invention. The drawings anddescriptions are exemplary of various aspects of the invention and arenot intended to narrow the scope of the appended claims.

As used herein, the term “ferromagnetic,” “ferromagnet,” and“ferromagnetism” refers to any ferromagnetic-like material that iscapable of producing heat via magnetic induction, including but notlimited to ferromagnets and ferrimagnets.

Turning now to FIG. 1, there is shown a perspective view of a thermalsurgical tool system, generally indicated at 10. As will be discussed inadditional detail below, the thermal tool system preferably uses aferromagnetic coated conductor to treat or destroy tissue (i.e.endothelial tissue welding, homeostasis, ablation, etc).

It will be appreciated that the thermal surgical tool uses heat toincise tissue and does not cut tissue in the sense of a sharp edge beingdrawn across the tissue as with a conventional scalpel. While theembodiments of the present invention could be made with a relativelysharp edge so as to form a cutting blade, such is not necessary as theheated coating discussed herein will separate tissue without the needfor a cutting blade or sharp edge. However, for convenience, the termcutting is used when discussing separating tissue.

In the embodiment shown as thermal surgical tool system 10, a controlmechanism, such as a foot pedal 20 is used to control output energyproduced by a power subsystem 30. The energy from the power subsystem 30may be sent via radio frequency (RF) or oscillating electrical energyalong a cable 40 to a handheld surgical tool 50, which contains aconductor 60 having a section thereof coated with a ferromagneticcoating 65. The ferromagnetic coating 65 may transfer the electricalenergy into available thermal energy via induction and correspondinghysteresis losses in the ferromagnetic material disposed around aconductor wire 66. (While conductor wire is used for ease of reference,it will be appreciated that the conductor material need not be a wireand those skilled in the art will be familiar with multiple conductorswhich will work in light of the disclosure of the present invention).

Application of a magnetic field (or magnetizing) to the ferromagneticcoating may produce an open loop B-H curve (also known as an openhysteresis loop), resulting in hysteresis losses and the resultantthermal energy. Electrodeposited films, such as a nickel-iron coatinglike PERMALLOY™, may form an array of randomly aligned microcrystals,resulting in randomly aligned domains, which together may have an openloop hysteresis curve when a high frequency current is passed throughthe closely coupled conductor.

The RF energy may travel along the conductor's surface in a manner knownas the “skin effect”. The alternating RF current in the conductor'ssurface produces an alternating magnetic field, which may excite thedomains in the ferromagnetic coating 65 that is in close proximity tothe surface of the conductor. As the domains realign with eachoscillation of the current, hysteresis losses in the coating may causeinductive heating.

The RF conductor from the signal source up to and including the tip, mayform a resonant circuit at a specific frequency (also known as a tunedcircuit). Changes in the tip “detune” the circuit. Thus, should theferromagnetic coating 65 or the conductor wire 66 become damaged, thecircuit may likely become detuned. This detuning should reduce theefficiency of the heating of the ferromagnetic coating 65 such that thetemperature will be substantially reduced. The reduced temperatureshould ensure little or no tissue damage after breakage.

A breakage or other fault may also be detected by a sensor.Interruptions to normal circuit operation may thus be detected and causethe surgical system to shut down. In one embodiment, current ismonitored. If a sudden unexpected increase in current is detected, thesystem may shut down because the ferromagnetic coating may be no longerbe dissipating the power it should. Similarly, impedance may bemonitored and used as an indicator of a system fault.

It should be understood that the handheld surgical tool 50 may includeindicia of the power being applied and may even include a mechanism forcontrolling the power. Thus, for example, a series of lights 52 could beused to indicate power level, or the handheld surgical tool 50 couldinclude a switch, rotary dial, set of buttons, touchpad or slide 54 thatcommunicates with the power source 30 to regulate power and therebyaffect the temperature at the ferromagnetic coating 65 to having varyingeffects on tissue. These indicia may display the current status asrepresented by the power source and communicated to a user adjustablecontrol by the power source. While the controls are shown on the footpedal 20 or the handheld surgical tool 50, they may also be included inthe power subsystem 30 or even a separate control instrument. Safetyfeatures such as a button or touchpad that must be contacted to powerthe handheld surgical tool 50 may be employed, and may include a deadman's switch.

While the ferromagnetic coating 65 heats through induction, it alsoprovides a temperature cap due to its Curie temperature. A Curietemperature is the temperature at which the material becomesparamagnetic, such that the alignment of each domain relative to themagnetic field decreases to such an extent that the magnetic propertiesof the coating are lost. When the material becomes paramagnetic, theheating caused by induction may be significantly reduced or even cease.This causes the temperature of the ferromagnetic material to stabilizearound the Curie temperature if sufficient power is provided to reachthe Curie temperature. Once the temperature has dropped below the Curietemperature, induction may again start causing heating of the materialup to the Curie temperature. Thus, the temperature in the ferromagneticcoating may reach the Curie temperature during inductive heating withthe application of sufficient power, but will not likely exceed theCurie temperature.

The thermal surgical tool system 10 allows the power output to beadjustable in order to adjust the temperature of the tool and its effecton tissue. This adjustability gives the surgeon precise control over theeffects that may be achieved by the handheld surgical tool 50. Tissueeffects such as cutting, hemostasis, tissue welding, tissue vaporizationand tissue carbonization occur at different temperatures. By using thefoot pedal 20 (or some other user control) to adjust the power output,the surgeon (or other physician, etc.) can adjust the power delivered tothe ferromagnetic coating 65 and consequently control the tissue effectsto achieve a desired result.

Thermal power delivery can be controlled by varying the amplitude,frequency or duty cycle of the alternating current waveform, oralteration of the circuit to affect the standing wave driving theferromagnetic coated conductor, which may be achieved by input receivedby the foot pedal 20, the power subsystem 30, or the controls on thehandheld surgical tool 50.

For example, it is known that different temperatures are desirable forinducing different effects on tissue. As will be explained in additionaldetail below, certain temperatures can be used for welding tissues,while other temperatures will induce cutting, tissue ablation andvaporization.

One advantage of the present invention is that it enables the surgeon tocontrol power to the system, which ultimately affects the temperature atthe ferromagnetic coating 65 which can be applied to the tissue. Powercan be adjusted by multiple methods. Pulse width modulation can be usedto change the amount of time the ferromagnetic coating 65 is beingheated, thereby controlling the temperature. Amplitude modulation can beused to likewise control the power through the system and the ultimatetemperature dynamics of the ferromagnetic coating 65. As the RFconductor from the signal source to the tip, including the tip, may forma resonant circuit at a specific frequency (also known as a tunedcircuit), changes in the tip “detune” the circuit. Thus, frequencymodulation can be used to effectively temporarily detune the circuit andthereby ultimately control the temperature for tissue welding, cutting,etc. An exemplary circuit may use a phase locked loop or frequencysynthesizer to adjust frequency.

Power to the system can be controlled by a regulating structure, suchas, for example, the foot pedal 20. The pedal may have set points whichindicate to the surgeon the power which is being supplied. This can beaccomplished, for example, by having a pedal which has five positions,with each position requiring more force. The change in force requiredwill alert the surgeon to the temperature range that is being applied.

The power controller, such as a pedal, can also be used to send a signalto the surgeon as to the power level being applied at the ferromagneticcoating 65 or the energy available at the coating available for deliveryto the tissue. This could be an auditory or visual indicator 22 whichgives the surgeon a signal to indicate the power level. For example, iffive power levels are provided, an auditory alarm may indicate the powerlevel being applied. One chime for level or range 1, two chimes forlevel or range 2, three chimes for level or range 3, etc. Similarly,five distinct auditory signal tones could be used to indicate the fivepower levels.

Likewise the tool 50 could include indicia of the power being appliedand could even include a mechanism for controlling the power. Thus, forexample, a series of lights 52 could be used to indicate power level, orthe tool 50 could include a switch, rotary dial, set of buttons,touchpad or slide 54 that communicates with the power source 30 toregulate power and thereby affect the temperature at the ferromagneticcoating 65 to having varying effects on tissue. While the controls areshown on the foot pedal 20 or the tool 50, it may also be included inthe power subsystem 30 or even a separate control instrument. Similarly,safety features such as a button or touchpad that must be contacted topower the tool 50 may be employed, such as a dead man's switch.

One additional advantage achieved by the inductive heating is that theferromagnetic material can be heated to a cutting temperature in a smallfraction of a second (typically as short one quarter of a second).Additionally, because of the relatively low mass of the coating, thesmall thermal mass of the conductor, and the localization of the heatingto a small region due to construction of the handheld surgical tool 50,the material will also cool extremely rapidly (i.e. approximately onehalf of a second). This provides a surgeon with a precise thermal toolwhile reducing accidental tissue damage caused by touching tissue whenthe thermal tool is not activated.

It will be appreciated that the time period required to heat and coolthe handheld surgical tool 50 will depend, in part, on the relativedimensions of the conductor 60 and the ferromagnetic coating 65 and theheat capacity of the structure of the surgical tool. For example, theabove time periods for heating and cooling of the handheld surgical tool50 can be achieved with a tungsten conductor having a diameter of about0.375 mm and a ferromagnetic coating of a Nickel Iron alloy (such asNIRON™ available from Enthone, Inc. of West Haven, Conn.) about thetungsten conductor about 0.0375 mm thick and two centimeters long.

One advantage of the present invention is that a sharp edge is notneeded. When power is not being supplied to the surgical tool, the toolwill not inadvertently cut tissue of the patient or of the surgeon if itis dropped or mishandled. If power is not being supplied to theconductor wire 66 and coating 65, the “cutting” portion of the tool maybe touched without risk of injury. This is in sharp contrast to acutting blade which may injure the patient or the surgeon if mishandled.

Other additions may also be placed on the handpiece in variouslocations. This may include a sensor stem 12 including a sensor toreport temperature or a light to illuminate the surgical area.

Turning now to FIG. 2, a perspective view of an alternate embodiment ofa thermal surgical system 10 is shown. In FIG. 2, the power source 30 iscontained within the foot pedal 20. Depending on the application andpower required, the instrument may even be entirely battery powered forrelatively low power applications. An alternate embodiment for low powerrequirements may include the battery, power adjustment and powerdelivery, all self-contained in the handle 51 of the handheld surgicaltool 50. Furthermore, a wireless communication module can be employed tosend and receive information from the handheld surgical tool 50,including status and control settings that would enable users to monitorsystem performance and alter power settings remotely from the handheldsurgical tool 50 itself.

It is our understanding that this thermal solution may provideadvantages over monopolar and bipolar electrical systems currentlyavailable because the thermal damage may remain very close to theferromagnetic surface of the coated region, whereas monopolar andbipolar electrical tissue ablation may frequently cause tissue damagefor a distance away from the point of contact. It is our understandingthat this method may also overcome disadvantages of other thermaldevices based upon resistive heating, which may require more time toheat and cool, and thus present greater patient risk, while potentiallyhaving higher power requirements at the point of heating.

Furthermore, the thin ferromagnetic coating 65, disposed along a smallsegment of the conductor, may reduce the heating of other non-targetmaterial in the body, such as blood when working within the heart inatrial ablation—which can lead to complications if a clot is formed. Thesmall thermal mass of the conductor wire 66, and localization of theheating to a small region provided by the construction of the tool (i.e.ferromagnetic coating 65 and adjacent structures) provides a reducedthermal path for heat transfer in directions away from the location ofthe ferromagnetic coating 65. This reduced thermal path may result inthe precise application of heat at only the point desired. As thistechnology alone does not employ a spark or an arc like monopolar orbipolar technology, risks of ignition, such as by anesthetic gasseswithin or around the patient by sparks, are also reduced.

The thermal surgical tool system 10 may be used for a variety oftherapeutic means—including sealing, “cutting” or separating tissue,coagulation, or vaporization of tissue. In one configuration, thethermal surgical tool system 10 may be used like a knife or sealer,wherein the surgeon is actively “cutting” or sealing tissue by movementof the ferromagnetic coating 65 through tissue. The thermal action ofthe embodiments disclosed here may have distinct advantages includingsubstantial reduction, if not elimination, of deep tissue effectscompared with those associated with monopolar and bipolar RF energydevices.

In another configuration, the ferromagnetic coated conductor 60 may beinserted into a lesion and set to a specific power delivery or variablepower delivery based on monitored temperature. The thermal effects onthe lesion and surrounding tissue may be monitored until the desiredthermal effect is achieved or undesired effects are noticed. Oneadvantage of the application of the ferromagnetic coated conductor isthat it may be cost-effective compared to microwave or thermal lasermodalities and avoids the undesired tissue effects of microwave lesiondestruction. Thus, for example, a surgeon can insert the ferromagneticcoated conductor into a tumor or other tissue to be destroyed andprecisely control the tissue damage that is created by activating thehandheld surgical tool 50.

Sensors may be used to monitor conditions of the handheld surgical tool50, the electrical path, or the tissue, such as an infrared detector onsensor stem 12. For instance, the temperature of the device or tissuemay be important in performing a procedure. A sensor in the form of athermocouple, a junction of dissimilar metals, thermistor or othertemperature sensor may detect or conduct a measurement of thetemperature at or near the ferromagnetic coating 65 or tissue. Thesensor may be part of the device, such as a thermocouple placed as apart of the conductor, along, adjacent or near the ferromagneticcoating, or separate from the handheld surgical tool 50, such as aseparate tip placed near the tissue or ferromagnetic coating 65. Somesensors may measure indicators that correlate to a desired measurement,but are indirectly related. For example, temperatures may also becorrelated with tissue effects, seen in FIG. 27. Other useful conditionsto monitor may include, but are not limited to, power delivered at thecoating, tissue color, spectral absorption or reflection, conductor ortissue temperature range, tissue water content, proximity between thetissue and the conductor, tissue type, transferred heat, tissue status,impedance, resistance, return current, standing wave ratio (SWR),reflected power, reactance, center frequency, phase shift, voltage,current and visual feedback (i.e. a camera, fiberoptic or othervisualization device).

The power supply may be configured to respond to sensor feedback.Depending on the desired application, the sensor may provide usefulinformation in regulating or determining the output of the power supply.In one embodiment, the sensor sends a temperature reading to the powersupply. The power supply may then increase or decrease power delivery toremain at or near the desired temperature range. In another embodiment,the sensor communicates a water content reading to the power supplyduring tissue ablation. If the water content drops below a desiredlevel, the power supply may reduce the power setting as the tissue maybe sufficiently dessicated. Other sensors may provide useful input thatmay call for other settings to change on the power supply, such aswaveform, duration, timing or power settings.

The handheld surgical tool 50 may be configured for repeat sterilizationor single patient uses. More complex devices may be useful for repeatsterilization, while more simple devices may be more useful for singlepatient use.

A method for treating or cutting tissue may include the steps of:selecting a surgical tool having a cutting edge and a conductor disposedadjacent the cutting edge, at least a portion of which is coated with aferromagnetic material; cutting tissue with the cutting edge; andapplying oscillating electrical energy to the conductor to heat theferromagnetic material and thereby treating the cut tissue.

Optional steps of the method may include the steps of: causinghemostasis within the cut tissue; using the heated ferromagneticmaterial to incise tissue; or using the heated ferromagnetic material tocause vascular endothelial welding.

Referring now to FIG. 3, a diagram of an embodiment of the adjustablethermal surgical tool system 10 is shown. The power delivery to theferromagnetic coating 65 is controlled by a modulated high frequencywaveform. The modulated waveform allows power delivery to be controlledin a manner that adjustably modifies, allows or blocks portions of thewaveform based on the desired power delivery.

In FIG. 3, an initial waveform 110 is passed through a modulator 120receiving commands from a foot pedal 20. The waveform is created by anoscillator 130 to the desired frequency, and modulated by the modulator120, which may include, but is not limited to, one or more of amplitude,frequency or duty cycle modulation, including a combination thereof. Theresultant signal is then amplified by an amplifier 140. The amplifiedsignal is sent across a tuned cable 150, meaning that the cable is tunedto provide a standing wave with maximum current and minimum voltage atthe location of the ferromagnetic coating 65 of the handheld surgicaltool 50. Alternatively, the cable 150 may not be tuned, but a circuitmay be placed in the handle 51 to impedance match the ferromagneticcoated conductor 60 as a load to the power source 30.

The thermal surgical tool system 10 may be tuned by specifying thelocation of the ferromagnetic coating 65 with respect to the amplifier140 (such as cable length) and tuning the high frequency signal toapproximately a resonant standing wave such that current is maximized atthe location of the ferromagnetic coating 65.

It should be recognized that the surgical tool may operate in a dynamicenvironment. Thus when used herein, approximately a standing wave meansthat a circuit may be tuned such that the signal may be near an optimalstanding wave but may not achieve it, may only achieve the wave forsmall amounts of time, or may successfully achieve a standing wave forlonger periods of time. Similarly, any use of “standing wave” withoutthe modifier of approximate should be understood to be approximate inthe context of the thermal surgical tool.

One method for achieving such current maximization is to connect theferromagnetic coated conductor 60 to a cable 150 that is effectively anodd multiple of one-quarter wavelengths in length and connected to theoutput of the amplifier 140. The design of the circuit having a resonantstanding wave is intended to optimize power delivery to theferromagnetic coating. However, in one embodiment, the power source 30could be positioned at the location of (or closely adjacent to) theferromagnetic coating 65, and tuning could be achieved with electricalcomponents, all within a single handheld, battery-powered instrument.Alternatively, electrical components necessary for impedance matchingcan be located at the output stage of the amplifier 140. Further,electrical components, such as a capacitor or inductor, can be connectedin parallel or series to the ferromagnetic coated conductor 60 at thelocation of the connection of the conductor wire 66 to the cable 150, inorder to complete a resonant circuit.

Dynamic load issues can be caused by the interaction of theferromagnetic coated conductor 60 with various tissues. These issues maybe minimized by the standing current wave (or at least one standing waveor waveform) being maximized at the load location. Multiple differentfrequencies can be used, including frequencies from 5 megahertz to 24gigahertz. It is currently believed that that a waveform, preferablybetween 40 megahertz to 928 megahertz is desirable.

In some regulated countries it may be preferable choose frequencies inthe ISM bands such as bands with the center frequencies of 6.78 MHz,13.56 MHz, 27.12 MHz, 40.68 MHz, 433.92 MHz, 915 MHz, 2.45 GHz, 5.80GHz, 24.125 GHz, 61.25 GHz, 122.5 GHz, 245 GHz. In one embodiment, theoscillator 130 uses an ISM Band frequency of 40.68 MHz, a class Eamplifier 140, and a length of coaxial cable 150, all of which may beoptimized for power delivery to a ferromagnetic coated tungstenconductor 60 with a ferromagnetic coating 65 consisting of a thicknessof between 0.05 micrometer and 500 micrometers, and preferably between 1micrometer and 50 micrometers. A useful estimate may be to start theferromagnetic coating thickness at 10% of the conductor diameter, and upto 5 cm long. However, the ferromagnetic coating may be disposed as faralong the length or along multiple regions of the conductor as whereheating may be desired. (The ferromagnetic coating 65 may be formed froma Nickel Iron (NiFe) alloy, such as NIRON™ from Enthone, Inc. of WestHaven, Conn., or other ferromagnetic coatings, including Co, Fe,FeOFe₂O₃, NiOFe₂O₃, CuOFe₂O₃, MgOFe₂O₃, MnBi, Ni, MnSb, MnOFe₂O₃,Y₃Fe₅O₁₂, CrO₂, MnAs, Gd, Dy, EuO, magnetite, yttrium iron garnet,aluminum, PERMALLOY™, and zinc.)

The size of the conductor, size of the ferromagnetic coating, associatedthicknesses, shape, primary geometry, composition, power supply andother attributes may be selected based on the type of procedure andsurgeon preferences. For example, a brain surgeon may desire a smallinstrument in light handheld package designed for quick applicationwithin the brain, while an orthopedic surgeon may require a largerdevice with more available power for operation on muscle.

The conductor may be formed from copper, tungsten, titanium, stainlesssteel, platinum and other materials that may conduct electricity.Considerations for the conductor may include, but are not limited tomechanical strength, thermal expansion, thermal conductivity, electricalconduction/resistivity, rigidity, and flexibility. It may be desirableto form the conductor wire 66 from more than one material. Connection oftwo dissimilar metals may form a thermocouple. If the thermocouple wereplaced in the vicinity or within of the ferromagnetic coating, thethermocouple provides a temperature feedback mechanism for the device.Further, some conductors may have a resistivity that correlates totemperature, which may also be used to measure temperature.

The tuning of the power source 30 also reduces the amount of highfrequency energy radiating into the patient to near zero, as voltage islow, and ideally zero, at the location of the ferromagnetic coating 65.This is in contrast to monopolar devices, which require a grounding padto be applied to the patient, or bipolar devices, both of which passcurrent through the tissue itself. The disadvantages of these effectsare well known in the literature.

In many of these embodiments discussed herein, the combination of cablelength, frequency, capacitance and inductance may also be used to adjustefficiency and tool geometry by tuning the power source 30 to delivermaximum power to the ferromagnetic coating 65, and therefore, maximumheat to the tissue. A tuned system also provides for inherent safetybenefits; if the conductor were to be damaged, the system would becomedetuned, causing the power delivery efficiency to drop, and may evenshut down if monitored by an appropriate safety circuit.

The amount of power delivered to the patient tissue may be modified byseveral means to provide precise control of tissue effects. The powersource 30 may incorporate a modulator 120 for power delivery asdescribed above. Another embodiment uses modification of the magneticfield by altering the geometry of the conductor wire 66 and theferromagnetic coating 65 through which it passes, such as would becaused by a magnet. Placement of the magnet nearby the ferromagneticcoating 65 would similarly alter the induction effect and thereby changethe thermal effect.

Different forms of modulation may be used to control delivery of power.Pulse width modulation is based on the principle that the ferromagneticcoating acts as a thermal integrator. Amplitude modulation may controlpower delivery by altering a continuous waveform so that only thedesired power is delivered. Frequency modulation may “detune thecircuit” or change the standing wave ratio causing losses to occur intransmission such that the full power is not delivered to the load.

While modulation has been discussed as a method to control powerdelivery, other methods may be used to control power delivery. In oneembodiment, the output power, and correspondingly the temperature, ofthe tool is controlled by tuning or detuning the drive circuit,including the conductor wire 66 and ferromagnetic coated conductor 60.

A process of delivering power to a thermally adjustable tool may includethe steps of: selecting a surgical tool comprising a conductorconfigured such that an oscillating electrical signal will haveapproximately a standing wave with maximum current and minimum voltageat a load, the load consisting of a ferromagnetic material coated on theconductor; delivering the oscillating electrical signal to the load; andcausing the electrical signal to no longer be sent to the load.

The process may optionally include the steps of: providing a oscillatingelectrical signal between the frequencies of 5 megahertz and 24gigahertz; or providing an oscillating electrical signal selected fromthe group of center frequencies of 6.78 MHz, 13.56 MHz, 27.12 MHz, 40.68MHz, 433.92 MHz, 915 MHz, 2.45 GHz, 5.80 GHz, 24.125 GHz, 61.25 GHz,122.5 GHz, 245 GHz.

A method of incising tissue may include the steps of: selecting aconductor having a ferromagnetic coating disposed on a portion thereof;disposing the ferromagnetic coating into contact with the tissue; anddelivering an oscillating electrical signal to the conductor so as toheat the ferromagnetic coating and cut the tissue.

The method may optionally include the step of selecting a power outputof the oscillating electrical signal. The power output may correspond toa temperature range at the ferromagnetic coating or a desired tissueeffect. The temperature range may be selected for a corresponding tissueeffect of cutting, hemostasis, vascular endothelial welding, tissuevaporization, tissue ablation and tissue carbonization.

An alternative method for incising tissue may include the steps of:selecting a conductor having a ferromagnetic coating disposed on aportion thereof, which is associated with a plug; placing the plug intoa receptacle configured for power delivery; disposing the ferromagneticcoating into contact with the tissue; and delivering an oscillatingelectrical signal to the conductor through the plug so as to heat theferromagnetic coating and incise the tissue.

The method may optionally include the steps of: removing the plug afteruse; communicating the characteristics of the conductor andferromagnetic coating; accessing a computer chip within the plug; orcommunicating a resistor value corresponding to characteristics in alookup table.

A method for performing surgery may include the steps of: selecting aload comprising a conductor with a ferromagnetic coating; deliveringpower to the conductor through oscillating electrical energy from apower source; and matching an impedance of the load to an impedance ofthe generator.

The method may optionally include the steps of: changing the outputimpedance of the power source to match the load; altering the frequencyof the oscillating electrical energy; adjusting the power source toachieve a standing wave in the oscillating electrical energy; maximizingcurrent at the conductor; choosing components to achieve a standing waveat the conductor; or selecting a length of cable to connect the powersource to the electrical conductor to achieve a standing wave at theconductor.

A method for treating tissue may include the steps of: selecting aconductor having a ferromagnetic coating disposed on a portion thereof;disposing the ferromagnetic coating into contact with the tissue;delivering an oscillating electrical signal to the conductor so as toheat the ferromagnetic coating and treat the tissue; and adjusting auser control to alter the power delivered.

A method for cutting may include the steps of: selecting a conductor, aportion of the conductor having a ferromagnetic coating disposedthereon; delivering an oscillating electrical signal to the conductor tocause hysteresis in the ferromagnetic coating and thereby heat theferromagnetic coating; and applying the heated coating to a substance tobe cut to thereby cut the substance.

Turning now to FIG. 4A, a thermal surgical tool system 10 withconnectors which attach to opposing first and second ends of a wireconductor is shown. The conductors as shown in FIG. 4A may be formed byheat prevention terminals 280, such as crimp connectors that providethermal isolation. One or more heat sinks 282, and wirelesscommunication devices 286 may also be included. The wire conductor 220may be connected to the handheld surgical tool 50 by terminals 280and/or a heat sink 282 at opposing first and second ends of theconductor. Portions of the conductor may extend into the handle intoterminals, while the ferromagnetic coating portion of the conductor mayextend beyond the handle. The terminals 280 may have a poor thermalconductance such that the terminals 280 reduce the heat transfer fromthe conductor into the handheld surgical tool 50. In contrast, the heatsink 282 may draw any residual heat from the terminals 280 and dissipatethe heat into other mediums, including the air. Connectors andconnections may also be achieved by wire bonding, spot and otherwelding, in addition to crimping.

Preventing thermal spread may be desirable because the other heatedportions of the handheld surgical tool 50 may cause undesired burns,even to the operator of the handheld surgical tool 50. In oneembodiment, terminals 280 are used to conduct the electric current, butprevent or reduce thermal conduction beyond the ferromagnetic coatedconductor.

The thermal surgical tool may also communicate wirelessly. In oneembodiment, the user interface for monitoring and adjusting power levelsmay be housed in a remote, wirelessly coupled device 284. The wirelesslycoupled device may communicate with a wireless module 286 containedwithin the thermal surgical tool system 10, including the handheldsurgical tool 50, the control system (such as footpedal 20), and/or thepower subsystem 30. By housing the control interface and display in aseparate device, the cost of the handheld surgical tool 50 portion maybe decreased. Similarly, the external device may be equipped with moreprocessing power, storage and, consequently, better control and dataanalysis algorithms.

Turning now to FIG. 4B, a thermal surgical tool system with impedancematching network is shown. The impedance matching network may match theoutput impedance of the signal source to the input impedance of theload. This impedance matching may aid in maximizing power and minimizingreflections from the load.

In one embodiment, the impedance matching network may be a balun 281.This may aid in power transfer as the balun 281 may match the impedanceof the ferromagnetic coated conductor terminals 287 to the amplifiercable terminals 283 (shown here as a coaxial cable connection). In sucha configuration, some baluns may be able to act as a heat sink andprovide thermal isolation to prevent thermal spread from the thermalenergy at the ferromagnetic coating 65 transferred by the wire conductor220 to terminals 287. The appropriate matching circuitry may also beplaced on a ceramic substrate to further sink heat away or isolate heataway from the rest of the system, depending on the composition of thesubstrate.

It should be recognized that these elements discussed in FIGS. 4A and 4Bcan be used in conjunction with any of the embodiments shown herein.

Turning now to FIG. 5A, a longitudinal cross section of theferromagnetic coated conductor is shown. As an alternating current 67 ispassed through conductor 66, a time varying magnetic field 68 is inducedaround conductor 66. The time varying magnetic field 68 is resisted bythe ferromagnetic coating 65, causing the ferromagnetic coating 65 todissipate the inductive resistance to the time varying magnetic field 68as heat. Should the ferromagnetic coating 65 reach it's Curie point, themagnetic resistive properties of ferromagnetic coating 65 becomesubstantially reduced, resulting in substantially decreased resistanceto time varying magnetic field 68. As there is very little mass to theferromagnetic coating 65, the magnetic field causes the ferromagneticcoating 65 to quickly heat. Similarly, the ferromagnetic coating 65 issmall in mass compared to conductor 66 and therefore heat will quicklydissipate therefrom due to thermal transfer from the hot ferromagneticcoating 65 to the cooler and larger conductor 66, as well as from theferromagnetic coating 65 to the surrounding environment.

As is also evident from FIG. 5A, the ferromagnetic coating may bebetween a first section (or proximal portion) and a second section (ordistal portion) of the conductor. This may provide the advantage oflimiting the active heating to a small area, instead of the entireconductor. A power supply may also connect to the first and secondsection to include the ferromagnetic coating within a circuit providingpower.

A method of using the surgical tool may include the steps of: selectinga conductor and plating a ferromagnetic coating upon the conductor.

Optional steps to the method may include: selecting a size of aconductor having a ferromagnetic coating disposed on a portion thereofaccording to a desired procedure; selecting a thermal mass of aconductor having a ferromagnetic coating disposed on a portion thereofaccording to a desired procedure; selecting a conductor from the groupof loop, solid loop, square, pointed, hook and angled; configuring theoscillating electrical signal to heat the coating to between 37 and 600degrees Centigrade; configuring the oscillating electrical signal toheat the coating to between 40 and 500 degrees Centigrade; causing thecoating to heat to between about 58-62 degrees Centigrade to causevascular endothelial welding; causing the coating to heat to betweenabout 70-80 degrees Centigrade to promote tissue hemostasis; causing thecoating to heat to between about 80-200 degrees Centigrade to promotetissue searing and sealing; causing the coating to heat to between about200-400 degrees Centigrade to create tissue incisions; or causing thecoating to heat to between about 400-500 degrees Centigrade to causetissue ablation and vaporization. Treatment may include incising tissue,causing hemostasis, ablating tissue, or vascular endothelial welding.

Turning now to FIG. 5B, an electrical equivalent representation of aFIG. 5A's ferromagnetic coated conductor is shown. The ferromagneticcoating is represented as a transformer 72 with a dynamic resistance 74.The inductance of the ferromagnetic coated conductor varies based on thecurrent passing through the conductor. At a low operating frequency, theinductance of the coating will have a small impact. At a high operatingfrequency, inductance of the coating will have greater effect. Further,different ferromagnetic coated conductor tip configurations will havedifferent impedance characteristics. Therefore, it is necessary toprovide a means to match the amplifier output to loads having differentimpedances.

A variety of means are available to achieve desired impedance matching.A continuously adjustable matching network may change the matchingimpedance as the load changes, seeking to keep it optimal for powertransfer to the load. Thus, the generator may always have optimal powertransfer to the load through the network. This may include adjustingcapacitance, inductance or frequency of the network.

An advantageous design of the instrument is to employ minimal powerlevels from the amplifier necessary to achieve the desired therapeuticheating range. Continuous monitoring of signal characteristics, such asreturn current, standing wave ratio (SWR) or reflected power, becomepractical electrical methods both to maintain temporal heating andcooling properties and to achieve the desired temperature within afraction of a second.

In one embodiment, SWR is monitored. By monitoring and retuning tooptimize SWR, power transfer can be optimized for various ferromagneticcoated conductor tips.

Instead of measuring load characteristics, the load may bepre-characterized. Thus, the output impedance of the amplifier may becaused to change based on predicted characteristics of the load found inprior measurements. In one embodiment, the handle or handpiece cableconnector may have a receptacle which may match a plug with aferromagnetic coated conductor. The plug may contain informationidentifying the predicted load characteristics of the ferromagneticcoated conductor attached to the plug in a data module. The data modulemay then communicate the characterization to the generator or generatorcontrol. Thus the system may predict and match the load characteristicsby the information contained within the plug. This information mayfurther aid the system in predicting output power to temperaturecorrelations. Similar matching can be achieved with a plug that containsan electrical component, such as a resistor, that is correlated and usedto identify the configuration of the ferromagnetic coated conductor. Inthis case, the generator circuit would read the value of the resistorthat identifies the ferromagnetic coated conductor and automaticallyadjusts drive settings.

Instead of a generator having variable tuning, a driver having fixedoutput impedance may be employed to drive ferromagnetic coated conductortips having input impedances that are properly matched for optimal powertransfer. Because this matching network is static, it can be constructedin a variety of ways. One particularly simple method is to use adesignated, fixed length of cable between the generator and the load,placing the load at the optimal point where maximum power can betransferred. This approach requires more design effort for the surgicaltool but ultimately creates a physically simpler generator—that is,fewer parts and a less expensive system to build. Further, a balun maybe used for impedance matching as described above. These approaches mayeffectively maintain a constant current through the ferromagnetic coatedconductor.

In applications where the thermal load is dynamic, due to the changingthermal conductivity of the surgical environment, a variety of means areavailable to achieve and maintain desired tissue effects. A continuouslyadjustable amplifier may change the power level as the thermal loadchanges, seeking to keep power transfer to the load adequate to achieveand maintain desired tissue effects. Through the previously describedimpedance matching network, the generator may always have optimal powertransfer to the load through the network. If the changing thermal loadchanges the impedance of the ferromagnetic coated conductor, the poweroutput of the ferromagnetic coating may be maintained by continuouslyadjusting the network driving the ferromagnetic material, as its load,in order to keep the material in an optimized heating mode. This mayinclude adjusting capacitance, inductance or frequency of the network.

Methods similar to those described above for driving ferromagneticcoated conductors representing loads of varying impedance can be used toadapt to individual ferromagnetic coated conductors which change theirimpedance in changing surgical environments, including interaction withvarious tissues and liquids. Continuous monitoring of signalcharacteristics, such as return current, standing wave ratio (SWR) orreflected power, become practical electrical methods both to maintaintemporal heating and cooling properties and to achieve the desiredtemperature within a fraction of a second.

In one embodiment, SWR is monitored. By monitoring and retuning tooptimize SWR, power transfer can be optimized as the surgicalenvironment and heat transfer away from the ferromagnetic coatingchanges. Rapid retuning, which may be practically achievable at least at10 Hz, allows dynamic responsiveness for temperature as the surgicaldevice is moved in and out of the wet surgical environment and into theair.

It should be appreciated that while the figures show a solid circularcross-section, the conductor cross-section may have various geometries.For instance, the conductor may be a hollow tubing such that it reducesthermal mass. Whether solid or hollow, the conductor may also be shapedsuch that it has an oval, triangular, square or rectangularcross-section.

Turning now to FIG. 6, a close-up, longitudinal cross-sectional view ofa single layer cutting tip with a thermal insulator 310 is shown. Alayer of thermal insulator 310 may be placed between the ferromagneticcoating 65 and the conductor 66. Putting a layer of thermal insulator310 may aid in the quick heating and cool-down (also known as thermalresponse time) of the tool by reducing the thermal mass by limiting theheat transfer to the conductor 66.

The thickness and composition of the thermal insulator may be adjustedto change the power delivery and thermal response time characteristicsto a desired application. A thicker coating of thermal insulator 310 maybetter insulate the conductor 66 from the ferromagnetic coating 65, butmay require an increased power compared with a thinner coating ofthermal insulator 310 in order to induce a magnetic field sufficient tocause the ferromagnetic coating to heat.

In the embodiments shown in FIGS. 7A-7G a plurality of embodiments areshown in which the surgical tip 210 is a tool which includes a wireconductor 220 which has a portion of its length coated with a relativelythin layer of ferromagnetic coating 65. As shown in FIGS. 7A-7G, theferromagnetic coating 65 may be a circumferential coating around a wireconductor 220. When the wire conductor 220 is excited by a highfrequency oscillator, the ferromagnetic coating 65 will heat throughinduction according to the power delivered, with an absolute limitprovided by its Curie temperature. Because of the small thickness offerromagnetic coating 65 and the tuned efficiency of high frequencyelectrical conduction of the wire at the position of the ferromagneticcoating 65, the ferromagnetic coating 65 will heat very quickly (i.e. asmall fraction of a second) when the current is directed through thewire conductor 220, and cool down quickly (i.e. a fraction of a second)when the current is stopped.

Turning now to FIGS. 7A, 7B, 7C, 7D, 7E, 7F AND 7G, ferromagnetic coatedconductor surgical tips 210 a, 210 b, 210 c, 210 d, 210 e, 210 f and 210g are shown. In each of these embodiments, a portion of wire conductor220 is bent and coated with ferromagnetic coating 65 such that theferromagnetic coating 65 is only exposed to tissue where the desiredheating is to occur. FIGS. 7A and 7B are loop shapes that can be usedfor tissue cutting or excision, depending upon the orientation of thetool to the tissue. FIG. 7A shows a rounded geometry, while FIG. 7Bshows a squared geometry. FIG. 7C shows a pointed geometry for heatedtip applications that can be made very small because the process oftissue dissection, ablation, and hemostasis requires only a smallcontact point. FIG. 7D shows an asymmetric tool with a loop geometry,where the ferromagnetic coating 65 is only disposed on one side of thetool. FIG. 7E shows a hook geometry where the ferromagnetic coating 65is disposed on the concave portion of the hook. FIG. 7F shows a hookgeometry where the ferromagnetic coating 65 is disposed on the convexportion of the hook. FIG. 7G shows an angled geometry, which may be usedin similar situations as a scalpel. Use of these various geometries offerromagnetic coating 65 upon a wire conductor 220 may allow thesurgical tip to act very precisely when active and to be atraumatic whennon-active.

In one representative embodiment, the electrical conductor may have adiameter of 0.01 millimeter to 1 millimeter and preferably 0.125 to 0.5millimeters. The electrical conductor may be tungsten, copper, othermetals and conductive non-metals, or a combination such as twodissimilar metals joined to also form a thermocouple for temperaturemeasurement. The electrical conductor may also be a thin coating ofconductor, such as copper, dispersed around a non-metallic rod, fiber ortube, such as glass or high-temperature plastic, and the conductivematerial, in-turn, may be coated with a thin layer of ferromagneticmaterial. The magnetic film forms a closed magnetic path around theelectrically conductive wire. The thin magnetic film may have athickness about 0.01-50% and preferably about 0.1% to 20% of thecross-sectional diameter of the wire. Due to the close proximity of thecoating to the wire, a small current can produce high magnetic fields inthe coating and result in significant temperatures. Since the magneticpermeability of this film is high and it is tightly coupled to theelectrical conductor, low levels of current can result in significanthysteresis losses.

It is therefore possible to operate at high frequencies with lowalternating current levels to achieve rapid inductive heating up to theCurie point. The same minimal thermal mass allows rapid decay of heatinto tissue and/or the conductor with cessation of current. The tool,having low thermal mass, provides a rapid means for temperatureregulation across a therapeutic range between about 37 degrees Celsiusand 600 degrees Celsius, and preferably between 40 and 500 degreesCelsius.

While Curie point has been previously described as a temperature cap,instead, here a material with a Curie point beyond the anticipatedtherapeutic need may be selected and the temperature can be regulatedbelow the Curie point.

While some tip geometries are shown in FIGS. 7A through 7G, it isanticipated that multiple different geometries of the ferromagneticcoated conductor 60 may be used.

Turning now to FIG. 8, a cut-away view of a snare 350 in a retractedposition is shown. A ferromagnetic coating is placed on a conductor toform a snare loop 355 and then placed within a sheath 360. Whileretracted, the snare loop 355 may rest within a sheath 360 (or someother applicator, including a tube, ring or other geometry designed toreduce the width of the snare when retracted). The sheath 360 compressesthe snare loop 355 within its hollow body. The sheath 360 may then beinserted into a cavity where the target tissue may be present. Once thesheath 360 reaches the desired location, the snare loop 355 may beextended outside the sheath 360, and end up deployed similar to FIG. 9A.In one embodiment, the conductor 365 may pushed or pulled to causeextension and retraction of the snare loop 355.

Turning now to FIG. 9A a side view of a snare 350 in an extendedposition is shown. Once extended, the snare 355 loop may be used inseveral different ways. In one embodiment, the snare loop 355 may beplaced substantially around the target tissue, such that the tissue iswithin the snare loop 355. The ferromagnetic coating may then be causedto be inductively heated as discussed above. The snare loop 355 is thenretracted back into the sheath 360 such that the target tissue isseparated and removed from tissue adjacent the target tissue. Thedesired temperature range or power level may be selected for hemostasis,increased tissue separation effectiveness or other desired setting. Forexample, in one embodiment, the snare 350 is configured for nasal cavitypolyp removal.

In another use, the snare 350 may be configured for tissue destruction.Once within the desired cavity, the snare may be extended such that aportion of the snare loop 355 touches the target tissue. The snare loop355 may then be inductively heated such that a desired tissue effectoccurs. For example, in one embodiment, the sheath may be placed near orin the heart and the snare loop 355 inductively heated to cause aninterruption of abnormal areas of conduction in the heart, such as inatrial ablation.

Turning now to FIG. 9B, an alternate embodiment of a snare 351 is shown.The applicator may be a ring 361 instead of a sheath as in FIG. 9A.Similar to the sheath, the ring 361 may be used to force the loop intoan elongated position. Various devices could be used to hold the ring inplace during use.

A method of separating tissue may include the steps of: selecting aconductor having a ferromagnetic coating disposed on a portion thereof;placing the portion of the conductor having the ferromagnetic coatingwithin a tube; inserting the tube into a cavity; deploying the portionof the conductor having the ferromagnetic coating within the cavity; anddelivering an oscillating electrical signal to the conductor so as toheat the ferromagnetic coating while the heated ferromagnetic coating isin contact with a target tissue.

Optional steps may include: deploying step further comprises placing theferromagnetic coating substantially around the target tissue; retractingthe ferromagnetic coating portion of the conductor into the tube;causing hemostasis in the target tissue; forming the conductor into abent geometry such that a portion of the conductor remains within thetube; and touching a ferromagnetic covered portion of the bent geometryto the target tissue.

A method of removing tissue may include the steps of: selecting aconductor having at least one portion having a ferromagnetic conductordisposed thereon; and placing the ferromagnetic conductor around atleast a portion of the tissue and pulling the ferromagnetic conductorinto contact with the tissue so that the ferromagnetic conductor cutsthe tissue.

Optional steps may include: using a conductor having a plurality offerromagnetic conductors in an array or passing an oscillatingelectrical signal through the conductor while the ferromagnetic materialis in contact with the tissue.

Turning now to FIG. 10A, a close-up view of a cutting tip with a loopgeometry and linear array of coatings is shown. While the aboveembodiments have disclosed a continuous ferromagnetic coating on aconductor, in another embodiment, there are more than one coatingseparated by gaps on a single conductor. This is termed a linear arrayof ferromagnetic elements (an example of a parallel array offerromagnetic elements can be seen in FIGS. 18A-18C).

In one embodiment, a loop geometry 270 a may have multiple ferromagneticcoatings 65, 65′, and 65″ which are separated by gaps on a wireconductor 220. In another embodiment shown in FIG. 10B, a close up viewof a cutting tip with an alternate hook geometry 270 b and linear arrayof ferromagnetic coatings 65 and 65′ is shown on a wire conductor 220.The linear array may include the advantage of allowing flexibility inbuilding a desired thermal geometry.

The conductor 220 which may be formed of an alloy having shape memory,such as Nitinol (nickel titanium alloy). A Nitinol or other shape memoryalloy conductor can be bent into one shape at one temperature, and thenreturn to its original shape when heated above is transformationtemperature. Thus, a physician could deform it for a particular use at alower temperature and then use the ferromagnetic coating to heat theconductor to return it to its original configuration. For example, ashape memory alloy conductor could be used to form snare which changesshape when heated. Likewise, a serpentine shape conductor can be made ofNitinol or other shape memory alloy to have one shape during use at agiven temperature and a second shape at a higher temperature. Anotherexample would be for a conductor which would change shape when heated toexpel itself from a catheter or endoscope, and then enable retractionwhen cooled.

In another embodiment, the ferromagnetic coatings may be formed in sucha way that an individual coating among the linear array may receive morepower by tuning the oscillating electrical energy. The tuning may beaccomplished by adjusting the frequency and/or load matching performedby the power source to specific ferromagnetic coatings.

Frequency response of individual coatings may be affected by alteringthe physical characteristics of the individual coatings. These physicalcharacteristics may include composition, thickness, length and proximityto other coatings. By altering the physical characteristics of eachcoating, the individual coatings may consume more power at an optimumfrequency for that coating. Other coatings may dissipate less or nopower at the same frequency. Thus it may be possible to addressindividual elements according to the frequency output by the generator.

Turning now to FIG. 11, a cut-away view of a snare tool 370 with alinear array of coatings in a retracted position is shown. In someembodiments, some ferromagnetic coatings may lack the elasticity toeffectively bend into a retracted position. Therefore, individualcoating segments 375 may be separated by gaps 380 such that theconductor 365 may be flexed while the coating segments 375 may remainrigid.

Similarly, the snare tool 370 may be extended, as seen in FIG. 12. Thegaps 380 between the coating segments 375 may be adjusted such that theheating effect will be similar in the gaps 380 as the coating segments.Thus, the snare tool 370 with linear array may act similar to the snarewith flexible coating in FIGS. 8 and 9.

Turning now to FIG. 13, a cross-sectional view of a single layer cuttingtip in the ferromagnetic-coated region is shown. The ferromagneticcoating 65 is disposed over a wire conductor 220. The ferromagneticcoating 65 provides several advantages. First, the ferromagnetic coating65 is less fragile when subjected to thermal stress than ferrite beads,which have a tendency to crack when heated and then immersed in liquid.The ferromagnetic coated conductor 60 has been observed to surviverepeated liquid immersion without damage. Further, the ferromagneticcoating 65 has a quick heating and quick cooling quality. This is likelybecause of the small amount of ferromagnetic coating 65 that is actedupon by the magnetic field, such that the power is concentrated over asmall area. The quick cooling is likely because of the small amount ofthermal mass that is active during the heating. Also, the composition ofthe ferromagnetic coating 65 may be altered to achieve a different Curietemperature, which would provide a maximum self-limiting thermal ceilingattribute to the device.

Turning now to FIGS. 14A, 14B and 15, a multilayer surgical tool tip isshown. A cross section of 14A along the 221 line may result in FIG. 14Bwhich shows alternating layers of wire conductor 220 and 220′ andferromagnetic coating 65 and 65′. Heating capacity may be increased bylayering thin layers of alternating conductor 220 and 220′ material andferromagnetic coating 65 and 65′, while still maintaining quick heatingand cooling advantages. FIG. 15 shows an axial cross-sectional view fromFIG. 14A along the 390 line. The alternating layers of conductor 220 and220′, and ferromagnetic coating 65 and 65′ may also be seen.

Turning now to FIG. 16, a flattened side cylindrical geometry is shown.The flat surface 180 can be manufactured to cause a thin plating 182 offerromagnetic coating on the conductor 66 relative to the thickerplating around the rest of the conductor 66. This thin plating 182 mayresult in selective first onset heating in this flat surface 180.Inductive heating may be proportional to flux density within themagnetically permeable coating. In one embodiment, an asymmetricallythinned coating has a small cross sectional thickness and will generatehigher hysteresis losses in the form of heat. Thus, a therapeutictemperature may be achieved with yet lower power at the flat surface 180with higher flux density 192 compared to a cooler opposite side with adiminished flux density 190. An advantage is that fast temporal responseand distributed optimal heating at the tissue interface may be enhanced.

Turning now to FIG. 17, the ferromagnetic coating 65 may also beconfigured to focus the temperature increase on the outside of theferromagnetic coating 65, further reducing the time needed to cool theferromagnetic coating 65 in a relatively high power application. Anexample of such a configuration is shown in FIG. 17, wherein the fieldsgenerated by the current flow 230 and 230′ (the arrows) may have acancelling effect with respect to each other within the ferromagneticcoating 65, keeping the ferromagnetic material between the loopedconductor 441 cooler than the ferromagnetic material at the perimeter.

Turning now to FIGS. 18A-18D, several surgical tip 194 geometries aredemonstrated. In FIG. 18A, a surgical tip 194 a with a single smalldiameter electrically conductive wire plated with the thin film magneticmaterial 196 is shown. In FIG. 18B, the surgical tip 194 b with twosmall diameter electrically conductive wires plated with the thin filmmagnetic material 196′ is shown. In FIG. 18C, a surgical tip 194 c withthree small diameter electrically conductive wires plated with the thinfilm magnetic material 196″ are shown. It is thus contemplated that atip geometry may consist of a plurality of small diameter electricallyconductive wires plated with the thin film magnetic material. Such adesign maintains the temporal heat responsiveness (rapid onset, rapidoffset) essential to the dynamic surgical environment due to minimalmass of the ferromagnetic coated conductor. It is thus possible toconfigure a flat tine with two or more spaced wires as a practicalmonothermal or multithermal tool. Further, the tips 194 a, 194 b and 194c may also be exchangeable as seen in FIG. 18D, which has a receptacle198 for the tips 194 in FIGS. 18A-18C. It will be appreciated that thegenerator system may be configured to adjust the power jointly deliveredto two or more of the conductors and that a user control (as shown inother figures) can be provided for that purpose.

The ferromagnetic coating 65 can be used to contact the tissue directly,or, a non-stick coating, such as TEFLON (PTFE), or similar material,could be applied over the ferromagnetic coating and conductor to preventsticking to the tissue. Alternatively, the ferromagnetic coating couldbe coated with another material, such as gold, to improvebiocompatibility, and/or polished, to reduce drag force when drawingthrough tissue. The ferromagnetic coating could also be coated by athermally-conductive material to improve heat transfer. In fact, asingle coating may be selected to have multiple desirable properties.

Turning now to FIGS. 19 to 22, the ferromagnetic coated conductor may beattached to a primary geometry. The primary geometry may provide anattachment surface or an internal site for the conductor with aferromagnetic coating. Thus the advantages of the ferromagnetic coatingon a conductor may be combined with the advantages of the primarygeometry and its corresponding material. The primary geometry may beselected for various reasons, including but not limited to, materialstrength, rigidity, heat conduction, resistance to thermal heattransfer, surface area, or additional functionality.

As used herein, a primary geometry means a structure to which aferromagnetic coated conductor may be attached and which defines theshape of the tool. For example, a primary geometry could be a scalpel,tines of forceps, the face of a spatula, or a ball shape at the end of aprobe. The conductor geometry, therefore, may be disposed upon theprimary geometry, may extend through a hole in the primary geometry,and/or be embedded in the primary geometry. For example, a primarygeometry may be a scalpel, while the conductor geometry may be theserpentine shape of a ferromagnetic coated wire upon the primarygeometry.

Turning now to FIGS. 19A and 19B, a cold cutting scalpel 223 withalternate inductive ferromagnetic thermal function is shown. The coldcutting scalpel 223 may be used for cutting through the application of ablade having a cutting edge and having a secondary thermal functionactivated when required, such as for coagulation. In the embodimentsshown in FIGS. 19A and 19B, this is achieved by placing a ferromagneticcoated wire conductor 220 upon the side of a scalpel shaped primarygeometry, which can cut or incise tissue without activation of theconductor or ferromagnetic coating 65. The cold cutting scalpel 223 maybe used classically to make incisions in tissue. However, if the patientbegins to bleed, the cold cutting scalpel 223 operator may activate theferromagnetic coated conductor and place the side of the cold cuttingscalpel 223 (and correspondingly, the ferromagnetic coated conductor)upon the bleeding tissue. The thermal effect may then cause the tissueto seal and cease bleeding. After deactivation of the ferromagneticcoated conductor, the scalpel operator may then return to makingincisions with the benefits of a cold cutting scalpel.

There are several advantages to use of such a cold cutting scalpel 223.The dual-use tool does not require the cold cutting scalpel 223 operatorto remove one tool and replace it with another, causing risk of furtherdamage and delay. Due to the ferromagnetic coating 65, the cold cuttingscalpel 223 may also have a quick thermal response time (the heat-up andcool-down time) in the region of the ferromagnetic coating 65 such thatthe cold cutting scalpel 223 may be used on the targeted area and reducewaiting time. In cases where it may be desirable to heat the entire coldcutting scalpel, thermal response time may be further reduced byremoving a center portion 222 of the blade, (as seen in FIG. 19B),resulting in a non-contiguous portion of the blade that may occurbetween or adjacent to the conductor path. Removing the center portion222 of the blade may further reduce the thermal mass and correspondinglythe thermal response time.

In one embodiment, related to FIG. 19B, the ferromagnetic coating may belimited to a part of the scalpel, such as the tip of the cold cuttingscalpel 223. This limiting would cause only the tip to heat, while theremaining portions of the primary geometry would remain at a lowertemperature. This limiting of the heating to a portion of the primarygeometry in proximity to the ferromagnetic coating may provide a higherdegree of accuracy and usefulness in smaller spaces. Similarly, theferromagnetic coated wire conductor 220 may form a pattern, such as azigzag or serpentine pattern, across the surface of the cold cuttingscalpel 223 to increase the heating coverage of the surface.

Scalpel effects may also be enhanced by the thermal effects of theferromagnetic coated wire conductor 220. In one embodiment, the scalpelmay have multiple parts with different temperature ranges addressable toeach part. For example, energy to the scalpel blade may be used to cut,while energy to the sides of the blade may be used to coagulate tissuewalls. In another embodiment, the ferromagnetic coated wire conductor220 may be activated to provide additional cutting ability when movingthrough more difficult tissue. In another embodiment, the ferromagneticcoated conductor may be activated to provide a more smooth cuttingprocess in conjunction with the scalpel blade. A user control may beused to select a power setting to be delivered by a power source, whichmay be correlated with a desired temperature or tissue effect.

The power supply may address individual coatings and their associatedconductors in a number of different ways. In one embodiment, theconductors have individual power lines, but share a common ground. Inanother embodiment, the conductors have individual power and groundlines. Another embodiment uses frequency modulation to addressindividual coatings. One digital embodiment uses three conductors. Oneconductor is used for communication about which coating should receivepower, while the other two are the power and ground signals. Analternative digital circuit removes the communication circuit andinstead sends a precursor identification signal on the power line suchthat the circuit can identify and direct the power to the correctcircuit. In fact, these technologies are not mutually exclusive, but maybe combined and used together. For example, the combination of circuitsmay be advantageous where some circuits require less power than othercircuits.

Turning now to FIG. 20A, a thermal surgical tool with a spatula shapedgeometry is shown. The spatula 224 may have a ferromagnetic coating 65on a wire conductor 220 that follows the perimeter of the spatula shapeas shown. In an alternate embodiment, the ferromagnetic coated portionof the wire conductor 220 may form a pattern across the surface of thegeometry such that the surface is more evenly covered by theferromagnetic coated portion of the wire conductor 220.

A spatula geometry may be useful for various tissue effects andprocedures. In one embodiment, the spatula is used for hemostasis ortissue welding during surgery. After an incision has been made, ifneeded, the spatula may be applied to the incised tissue to achievehemostasis or even tissue welding. In another embodiment, the spatulapressed into tissue and thermal energy is used for tissue ablation.

Turning now to FIG. 20B, the thermal surgical tool with a spatula shapedgeometry is shown in forceps form. The spatula forceps 225 may be usedin combination such that each spatula has a separate power control orthe forceps may have a power control in common. In other embodiments,the forceps may also only be heated on one spatula of the forceps. Sucha tool can be used to clamp vessels to stop blood flow, and then causehemostasis and cutting of the vessels with heat.

Turning now to FIGS. 20C and 20D, a side view of FIG. 20A is shown intwo different embodiments. The ferromagnetic coating and wire conductormay be attached to the primary geometry in several ways. In oneembodiment shown in 20C, the ferromagnetic coating 65 and conductor maybe attached to the surface of the primary geometry. Alternatively in20D, the ferromagnetic coating 65 and conductor may be embedded withinthe primary geometry. Depending upon the desired effect, the toolsdepicted in FIGS. 20A, 20B, 20C and 20D can be applied to tissue in sucha manner that the side of the tool on which the ferromagnetic coatedconductor 65 is located can contact the tissue, or the opposite side canbe applied to the tissue.

Turning now to FIGS. 21A, 21B and 21C, a thermal surgical tool with aball shaped geometry is shown. In one embodiment, a horizontally wrappedball 226 or a vertically wrapped ball 231 may be internally orexternally wrapped with a wire conductor 220 with a ferromagneticcoating 65 as seen in FIG. 21A and FIG. 21C. In another embodiment,shown in FIG. 21B, a ball geometry 227 may contain a wire conductor 220with a ferromagnetic coating prepared in another shape, such as ahorseshoe shape. In the embodiments, a ball-shaped heating element maybe formed which can be used to coagulate or provide a therapeutic effectover a large surface area of tissue. The ball may also be effective intissue ablation, as it may radiate thermal energy in most, if not all,directions.

Turning now to FIG. 22A, a thermal surgical tool with a pointed geometryis shown. The pointed tool 228 may have a ferromagnetic coating 65 on awire conductor 220 that follows the perimeter of the pointed tool shapeas shown. In an alternate embodiment, the ferromagnetic coated portionof the wire conductor 220 may form a pattern across the point surface ofthe geometry such that the point surface is more evenly covered by theferromagnetic coated portion of the wire conductor 220. The pointed tool228 may be particularly useful for making incisions that penetratelayers of tissue, providing a means for coagulation while cutting, suchas coagulation of tissue around the site of trocar insertion forlaparoscopic surgery.

Turning now to FIG. 22B, the thermal surgical tool with a pointedgeometry is shown in forceps form. The pointed forceps 229 may be usedin combination such that each pointed geometry has a separate powercontrol or the forceps may have a power control in common. Such a toolcan be configured for achieving hemostasis and cutting in small vesselligation.

While some primary geometries have been shown in singular form, theprimary geometries may be used in combination. This may include two ormore of the same primary geometry or differing primary geometries,including forceps applications. Each primary geometry may be commonlycontrolled for power or have separate power controls for each primarygeometry. Furthermore, solid primary geometries may be altered similarto the scalpel primary geometry shown above such that portions of theprimary geometries may be removed to reduce thermal mass andcorrespondingly, thermal response time.

While some of the primary geometries have been shown to have symmetricalconstruction, the primary geometries may have asymmetrical ordirectional construction such that only a portion of the primarygeometry would be active. This may be accomplished by placing theferromagnetic coating only on the portion of conductor wire residing onthe area of the primary geometry desired to be active. For example, thespatula geometry may be configured to be active in one area if theferromagnetic coated conductor is not symmetrically positioned on thespatula structure. This activation of only a part of the primarygeometry may be further enhanced by providing a pattern, such as azigzag or serpentine pattern, on the desired active portion of thegeometry, such as a surface.

In another embodiment, a portion of the primary geometry may beactivated. By using multiple conductors with a ferromagnetic coating 65attached to different portions of a primary geometry, a portion of theprimary geometry may be selectively activated. For example, a scalpelgeometry 232 may be divided into a tip portion 234 and a face portion236 as shown in FIG. 22C. A scalpel operator may then choose whether toactivate only the tip or the tip in conjunction with the face of thescalpel geometry, depending on the surface area desired. Similarly, in aforceps application, the forceps may be divided into inside and outsideportions. If the forceps operator desires to remove something that maybe surrounded by the forceps, such as a polyp, the internal portions maybe activated while the external portions remain deactivated. If opposingsides of a void need to be sealed, the outside surfaces of the forcepsmay be activated.

By using multiple conductors with a ferromagnetic coating 65 attached todifferent portions of a primary geometry and separately controlled powersources, different portions of the primary geometry may be activated atthe same time for different uses or effects. For example, an edgeportion of a primary geometry may be activated for cutting while theblade portion may be activated for hemostasis.

A method of treating tissue may thus include the steps of: selecting aprimary geometry having a conductor disposed thereon, the conductorhaving a ferromagnetic coating disposed on a portion thereof; disposingthe ferromagnetic coating into contact with the tissue; and deliveringan oscillating electrical signal to the conductor so as to heat theferromagnetic coating and treat the tissue.

Optional steps of the method may include choosing a primary geometryselected from the group of scalpel, spatula, ball and pointed geometry.Treating of the tissue may include incising, causing hemostasis,ablating or vascular endothelial welding.

A method for tissue destruction may include the steps of selecting aconductor having a ferromagnetic coating disposed on a portion thereof;and delivering an oscillating electrical signal to the conductor so asto heat the ferromagnetic coating and destroy tissue.

Optional steps of the method may include monitoring the tissue andceasing delivery of the oscillating electrical signal to the conductorwhen the desired tissue destruction has occurred or undesired tissueeffects are to be prevented.

A method for forming a surgical instrument may include the steps of:selecting a primary geometry; coating a conductor with ferromagneticmaterial; and disposing the conductor on the primary geometry.

Optional steps of the method may include providing electricalconnections on the conductor configured for receiving oscillatingelectrical energy.

Turning now to FIG. 23A, a catheter 270 having a conductor 220 which isat least partially coated with ferromagnetic material disposed aroundthe tip of the catheter is shown. Depending upon the therapeutic effectdesired, the location of the coil of ferromagnetic coating 65 couldinstead be inside the catheter tip, or a single loop of ferromagneticcoated conductor having a circumference which approximates that of thecatheter central channel 260 could be located at the end of the cathetertip.

In FIG. 23B, another ferromagnetic coated catheter 270 is shown. Whilein some embodiments the conductor may be a wire, coil, or annularstructure, a ferromagnetic coated catheter 270 could also be formedwhich would serve as an alternate conductor 250 with a ferromagneticcoating 65. In this embodiment, the catheter could consist of twocoaxial conductors, separated by an insulator. At the distal tip of thecatheter 270, a conductive coating can be applied such that a continuouselectrical path is created by the coaxial conductors. The ferromagneticcoating can be dispersed about the external diameter surface near thedistal tip of the catheter, as shown in FIG. 23B, or, upon the end ofthe catheter, on the annular surface connecting the coaxial conductors.This would allow the ferromagnetic coated catheter 270 to perform otherfunctions, such as irrigation, aspiration, sensing, or, to allow viewingaccess via optical fibers, through a central channel 260, as is commonin many interventional as well as open and minimally invasive surgicalprocedures. Furthermore, the central lumen of the catheter could be usedto provide access to other sensing modalities, including, but notlimited to, impedance and pH.

Turning now to FIG. 24, a side view of an alternate embodiment of aferromagnetic coated conductor surgical tool catheter tip 288 is shown.In one embodiment, the conductor may consist of a ferromagnetic coatedconductor positioned on a substrate 285 forming a body with a centralchannel. The ferromagnetic coating may consist of a plated ferromagneticcoating 275 on top of a conductor 289. The plating may be placed on theoutside of the substrate 285 such that the thermal effects are directedexternally. This may allow the catheter tip to apply thermal tissueeffects to tissue walls.

In another embodiment, the inside of the substrate may contain theconductor 289 and ferromagnetic coating 275 such that the thermaleffects are directed internally. An internal coating may allow deliveryof a meltable solid to a desired area, such as in fallopian tube sealingand osteosynthesis applications.

Alternatively, the ferromagnetic coating 275 may surround the entranceto the central channel 260, such that the thermal effects may bedirected in front of the tip. Having the thermal energy be directed infront of the central channel 260 entrance may aid in taking a tissuesample or removal of material, such as a polyp.

The plating may be accomplished through multiple methods. The substrate285 may be extruded, molded or formed from various materials includinghigh temperature thermoplastic, glass, or other suitable substratematerial. The actual plating may be accomplished through electroplating,electroless plating, vapor deposition, or etching, or some combinationthereof. Thus through the plating process, a catheter tip 288 may beformed with a ferromagnetic coating 275 on a conductor 280 with acontinuous path.

The catheter may also have multiple channels. One channel may be adeployment channel for the ferromagnetic coated conductor. Anotherchannel may be used for one or more sensors or sources, or even eachsensor or source in its own channel—such as a temperature sensor,illumination source and endoscope. Other channels may include delivery,irrigation or aspiration of substances, including those associated withtreatment, such as in osteosynthesis or fallopian tube sealing. In fact,the ferromagnetic coating may aid in the melting of such substances andthe coating may be directed at one or more specific channels rather thanthe catheter at large.

Turning now to FIG. 25, an endoscope 240 with a viewing channel 262 ofrod lens type or organized fiber bundle type aside a light emittingsource 266 is shown. A loop coagulator/cutter 264 is shown whichconsists of the ferromagnetic coated conductor 65. Such an adaptation iscontemplated in snare applications such as colon polypectomy or sealingand cutting applications in various laparoscopic procedures. Othersensing modalities include near field tumor cell detection or infraredheat monitoring. Tool configurations similar to the described endoscope240 can be embodied in tools that can be delivered to target tissuethrough the lumen of a catheter.

In one embodiment, tumor cells are caused to be tagged with materialsthat fluoresce when exposed to ultra-violet light. The endoscope 240 maycontain a light source, 266, and sensor or optics within the channel 262that return the detected florescence. The ferromagnetic coating 65portion of the endoscope 240 may then be directed at the tagged tissuefor destruction.

In another embodiment, materials are deposited around target tissue orbone in a solidified condition. Once delivered, the materials are meltedto conformation at the site by activation by the endoscope 240 describedabove. Examples of use of this embodiment include fallopian tube sealingand osteosynthesis. Furthermore, such materials could be removed bymelting with the same or similar endoscope 240, and aspirated through acentral lumen of the endoscope 240. In yet further applications,materials may be delivered in liquid form, and cured by a thermalheating process induced by the endoscope 240.

Alternatively, the conductor may be part of a bundle of fibers. Thefibers may be contained within a catheter or otherwise bundled together.The conductor may have a ferromagnetic coating, while the other fibersmay have other purposes that include visual observation, sensing,aspiration, or irrigation.

A method of tissue ablation may include the steps of: selecting acatheter with a ferromagnetic covered conductor; causing theferromagnetic covered conductor to touch tissue to be ablated; anddelivering power to the ferromagnetic covered conductor.

Optional steps may include: directing the catheter to the tissue throughthe aid of an endoscope; selecting a ferromagnetic coated conductordisposed on the catheter; selecting a ferromagnetic coated conductorcontained within the catheter; causing the ferromagnetic coatedconductor to be deployed from the catheter; or touching theferromagnetic coated conductor to the tissue to be ablated.

A method of delivering a substance into a body may include the steps of:selecting a catheter with a ferromagnetic coated conductor; placing asubstance in the catheter; inserting the catheter into a body; andcausing power to be sent to the ferromagnetic coated conductor.

Optional steps may include: selecting a substance for osteosynthesis;selecting a substance for fallopian tube sealing; or melting thesubstance in the catheter.

A method of treating tissue may include the steps of: selecting acatheter with a ferromagnetic coated conductor; placing the catheter incontact with tissue; and selecting a power setting. The temperaturerange may correspond to a temperature range or desired tissue effect.The desired tissue effect may be selected from the group of vascularendothelial welding, hemostasis, searing, sealing, incision, ablation,or vaporization. In fact, the power setting may correspond to a desiredtissue effect.

Turning now to FIG. 26, a tissue ablation tool 290 is shown. In typicalapplications of tissue ablation, an arm or tine 295 is inserted intoundesired tissue. One or more tips 300 may be activated such that thetissue temperature is raised to a desired level for a desired amount oftime. After the activation has succeed in holding a temperature for adesired amount of time, or undesired effects are noticed, the one ormore tips 300 may be deactivated and removed from the tissue.

In one embodiment, a conductor 220 may be contained in one or more armsor tines 295 with tips 300 that may contain ferromagnetic coatings 65.The tips 300 may be inserted into tissue and temperature controlleduntil tissue destruction occurs or one or more undesired tissue effectsoccur. The tissue effects may be monitored through sensors in the tines295 or externally.

Sensors may be placed in multiple ways. In one embodiment, the sensor isplaced in the tine and away from a ferromagnetic coated tip 300. Inanother embodiment, one tip 300 may have a ferromagnetic coating, whilean alternate tip 300 may have no coating, but a sensor contained within.The sensor may monitor tissue effects or some other indicator indicativeof the temperature of the ferromagnetic coated tip, properties of theassociated tissue, or some desired characteristic and may includevarious sensors, cameras and remote imaging. In another embodiment, thetemperature may be monitored through external imaging.

The sensor may thus form part of a feedback loop. By monitoring one ormore tissue effects, the ablation tool may self-adjust power settings.This self-adjustment may allow the system to operate below the Curiepoint and still maintain a desired tissue effect and/or temperaturerange.

In the case where more than one tip 300 is used, the tips 300 with aferromagnetic coating 65 may be individually controlled such that thethermal profile is concentrated in the desired area. This may also allowa second tine to monitor tissue effects, while a primary tine is used toperform the thermal function.

The power supply may individually address each tine. In one embodiment,the power supply monitors each tine for temperature. As tissue isdestroyed, the water content of the tissue may decrease. As watercontent decreases, the tissue may not require the same amount of thermalenergy. Thus, as tissue is destroyed, the power supply may monitortemperature and send less power or no power to tips 300 that showevidence of temperature spikes or changes.

While a diagram has been shown of a multi-tip tissue ablation tool inFIG. 26, a single tissue ablation tool may be made in a configurationsimilar to FIG. 7C.

Turning now to FIG. 27, a temperature spectrum is disclosed. Tissue mayreact differently at different temperatures with a tissue treatmentelement (such as a ferromagnetic coated conductor) and thus temperatureranges will result in different treatments for tissue. Specific tissuetreatments are somewhat variable due to inconsistencies including tissuetype and patient differences. The following temperatures have been foundto be useful. Vascular endothelial welding may be optimal at 58-62degrees Centigrade. Tissue hemostasis without sticking may be achievedat 70-80 degrees Centigrade. At higher temperatures, tissue searing andsealing may occur more quickly, but coagulum may build-up on theinstrument. Tissue incision may be achieved at 200 degrees Centigradewith some drag due to tissue adhesion at the edges. Tissue ablation andvaporization may occur rapidly in the 400-500 degree Centigrade range.Thus, by controlling the temperature the “treatment” of tissue which thedevice delivers can be controlled, be it vascular endothelial welding,tissue incision, hemostasis, tissue carbonization, tissue vaporizationor tissue ablation. According to the spectrum disclosed above, powerdelivery settings corresponding to the desired temperature range may beincluded in the power delivery switch. In one embodiment, the foot pedalmay have several stops that indicate to the surgeon the likely tiptemperature range of the current setting.

Besides the advantages of uses in tissue, the surgical tool may also beself-cleaning. In one embodiment, when activated in air, the tool mayachieve a temperature sufficient to carbonize or vaporize tissue debris.

It will be appreciated that the thermal surgical tool system inaccordance with the present invention will have a wide variety of uses.Not only can it be used on humans, it can also be use to cut tissue ofother animals, such as in the context of a veterinarian or simplycutting tissues or biomaterials, such as those used for implantation,into smaller pieces for other uses.

Certain embodiments of the surgical system may have broad applicationwithin surgery as well. A loop geometry may have advantages in cutting,coagulation and biopsy applications. A blade geometry may haveadvantages for cutting and hemostasis applications. The point geometrymay have advantages in dissection and coagulation applications, and inparticular, neurodissection and coagulation. However, the application ofa geometry may be further configured and tailored to an application bydiameter, length, material characteristics and other characteristicsdiscussed above.

While the present invention has been described principally in the areaof surgical tools and the treatment of live tissue (though it can beused on dead tissue as well), it will be understood that a tool made inaccordance with the present invention and the methods discussed hereinmay have other uses. For example, a cutting tool could be formed forbutchering meat. Whether the meat is fresh or frozen, the tool can beuseful. For example, a cutting blade which is heated to a hightemperature will cut through frozen meat. However, when power is nolonger supplied, the “cutting” edge is safe to the touch. Likewise,cutting meat with a hemostasis setting would slightly sear the exteriorof the meat, locking in juices. Other uses of the instruments discussedherein will be understood by those skill in the art in light of thepresent description.

There is thus disclosed an improved thermally adjustable surgical tool.It will be appreciated that numerous changes may be made to the presentinvention without departing from the scope of the claims.

1. A process of delivering power to a thermally adjustable surgical toolcomprising: selecting a surgical tool comprising a conductor configuredsuch that an oscillating electrical signal will have approximately astanding wave with maximum current and minimum voltage at a load, theload consisting of a ferromagnetic material coated on the conductor;delivering the oscillating electrical signal to the load; and causingthe electrical signal to no longer be sent to the load.
 2. The processaccording to claim 1, wherein the process comprises providing anoscillating electrical signal between the frequencies of 5 megahertz and24 gigahertz.
 3. The process according to claim 2, wherein theoscillating electrical signal is between the frequencies of 40 megahertzand 928 megahertz.
 4. The process according to claim 1, wherein theprocess comprises providing an oscillating electrical signal selectedfrom the group of center frequencies of 6.78 MHz, 13.56 MHz, 27.12 MHz,40.68 MHz, 433.92 MHz, 915 MHz, 2.45 GHz, 5.80 GHz, 24.125 GHz, 61.25GHz, 122.5 GHz, 245 GHz.
 5. A method for incising tissue, the methodcomprising; selecting a conductor having a ferromagnetic coatingdisposed on a portion thereof; disposing the ferromagnetic coating intocontact with the tissue; and delivering an oscillating electrical signalto the conductor so as to heat the ferromagnetic coating and cut thetissue.
 6. The method according to claim 5, further comprising the stepof selecting a power output of the oscillating electrical signal.
 7. Themethod according to claim 6, wherein the power output corresponds to atemperature range at the ferromagnetic coating.
 8. The method accordingto claim 7, wherein the temperature range is selected from the groupcorresponding to a desired tissue effect of cutting, hemostasis,vascular endothelial welding, tissue vaporization, tissue ablation andtissue carbonization.
 9. The method according to claim 6, wherein thepower output corresponds to a desired tissue effect.
 10. A method forincising tissue, the method comprising; selecting a conductor having aferromagnetic coating disposed on a portion thereof, which is associatedwith a plug; placing the plug into a receptacle configured for powerdelivery; disposing the ferromagnetic coating into contact with thetissue; and delivering an oscillating electrical signal to the conductorthrough the plug so as to heat the ferromagnetic coating and incise thetissue;
 11. The method of claim 10, further comprising removing the plugafter use.
 12. The method of claim 10, further comprising the step ofcommunicating characteristics of the conductor and ferromagnetic coatingthrough the receptical.
 13. The method of claim 12, wherein thecommunicating step further comprises the step of accessing a computerchip through or within the plug.
 14. The method of claim 12, wherein thecommunicating step further comprises the step of communicating aresistor value corresponding to characteristics in a lookup table.
 15. Amethod for performing surgery, the method comprising: selecting a loadcomprising a conductor with a ferromagnetic coating; delivering power tothe conductor through oscillating electrical energy from a power source;and matching an impedance of the load to an impedance of the generator.16. The method of claim 15, wherein the matching step further compriseschanging the output impedance of the power source to match the load. 17.The method of claim 15, wherein the matching step further comprisesaltering the frequency of the oscillating electrical energy.
 18. Themethod of claim 15, wherein the matching step further comprisesadjusting the power source to achieve a standing wave in the oscillatingelectrical energy.
 19. The method of claim 15, wherein the matching stepfurther comprises maximizing current at the conductor.
 20. The method ofclaim 15, wherein the matching step further comprises choosingcomponents to achieve a standing wave at the conductor.
 21. The methodof claim 15, wherein the matching step further comprises selecting alength of cable to connect the power source to the electrical conductorto achieve a standing wave at the conductor.
 22. A method for treatingtissue, the method comprising; selecting a conductor having aferromagnetic coating disposed on a portion thereof; disposing theferromagnetic coating into contact with the tissue; and delivering anoscillating electrical signal to the conductor so as to heat theferromagnetic coating and treat the tissue; adjusting a user control toalter the electrical signal to obtain or maintain a desired heating ofthe ferromagnetic coating.
 23. A method for cutting comprising:selecting a conductor, a portion of the conductor having a ferromagneticcoating disposed thereon; delivering an oscillating electrical signal tothe conductor to cause hysteresis in the ferromagnetic coating andthereby heat the ferromagnetic coating; and applying the heated coatingto a substance to be cut to thereby cut the substance.